444 H.C. Lewis—Zodvacal Inght. 
spreads out laterally along the horizon, and appears to be a 
purely atmospheric effect. 
nother kind of “moon zodiacal light” is described in a 
recent paper with the above title in the Proceedings of the 
American Acad. of Arts and Sciences.* Here the observer 
describes comet-like tails extending on each side of the moon 
to a distance of 8-10 times its diameter. The sky was soon 
after overcast with dense vapors, and after all such vapors had 
disappeared, these appearances also vanished. They were sup- 
posed to have a connection with both the zodiacal light and 
the aurora. 
Similar appearances have been observed by the present 
writer only upon similarly cloudy evenings, at which time dif- 
fraction caused by floating vapor might have explained what 
was seen. Since such phenomena have not been seen on clear 
evenings, it is thought that these effects are probably purely . 
atmospheric. 
The writer has not, as yet, been able to recognize in his 
observations any direct connection between the zodiacal light 
and the moon. 
The aurora appears to have no influence whatever upon any 
portion of the zodiacal band. 
The Horizon Light.—More than once in this paper, reference 
has been made to a light which it has been found convenient 
to designate by the above name. It has no connection what- 
ever with the zodiacal light; but since it is continually ob- 
served with that phenomenon, and at certain seasons of the 
year blends with and is apt to be confounded with portions of 
it, it Is necessary to take it into account. Unlike the zodiacal 
light, it is a terrestrial effect. 
ts brightness is variable. At times its lower portion seems 
* Proc. Amer. Acad, Arts and Sc., Noy., 1877, p. 183. 
